1. Field
The present embodiments relate to a technology that estimates a noise model for a sound obtained using a microphone.
2. Description of the Related Art
Hitherto, in order to perform a noise suppression process for suppressing noise of a sound signal received using a microphone; it has been determined whether or not a section for which a noise suppression process has been performed within the input sound signal is a voice section. Furthermore, it has been determined whether or not a section used for the target of a noise suppression process is stationary or non-stationary.
For example, Japanese Unexamined Patent Application Publication (Translation of PCT Application) No. 08-505715 discloses a method of determining whether a frame including a signal indicating a background sound is stationary or non-stationary. In the technology disclosed in Japanese Unexamined Patent Application Publication (Translation of PCT Application) No. 08-505715, the number of frames over which there is a continuous state in which the change in spectrum is small is measured, and a case in which the value thereof is greater than or equal to a threshold value is determined to be a stationary noise.
Furthermore, as a method for evaluating whether or not a section is a voice section, there is a method of using a correlation coefficient of a spectrum between adjacent frames as in, for example, International Publication 2004/111996. Furthermore, for example, Japanese Unexamined Patent Application Publication No. 2004-240214 discloses a technology using a correlation coefficient as a feature quantity of steadiness/unsteadiness for automatically making a determination regarding an acoustic signal.
Furthermore, as a noise suppression process of the related art, there is a spectral subtraction method. The spectral subtraction method is a method for suppressing noise by subtracting the value of a noise bias from a spectrum. For example, U.S. Pat. No. 4,897,878 relates to a spectrum subtraction method. The technology disclosed in Japanese Unexamined Patent Application Publication No. 2007-183306 corrects a spectrum after noise suppression to a target value when the target value of estimated noise is greater than a spectrum after noise suppression. Then, the technology disclosed in Japanese Unexamined Patent Application Publication No. 2007-183306 suppresses distortion of an output signal. As described above, in the noise suppression process, estimated values of noise are used for various applications.